This invention relates generally to folding tools, and more particularly to a folding tool that includes an automatic opener mechanism and including blades or tools capable of being locked in an open position.
Folding knives and tools suitable for many purposes are well known in the art. For example, U.S. Pat. No. 1,030,058 to Doles, U.S. Pat. No. 1,189,005 to Seely, U.S. Pat. No. 2,188,762 to Schrade, U.S. Pat. No. 3,868,774 to Miori, U.S. Pat. No. 4,233,737 to Peohlmann, U.S. Pat. No. 4,240,201 to Sawby et al., U.S. Pat. No. 4,274,200 to Coder, U.S. Pat. No. 4,451,982 to Collins, U.S. Pat. No. 4,502,221 to Pittman, U.S. Pat. No. 4,670,984 to Rickard, U.S. Pat. No. 4,837,932 to Elsener, U.S. Pat. No. 4,896,424 to Walker, U.S. Pat. No. 5,060,379 to Neely, U.S. Pat. No. 5,425,175 to Rogers, and U.S. Pat. No. 5,461,786 to Miller are representative of the available prior art.
As disclosed in several of the aforementioned patents, there are many different mechanisms for locking tool blades in an open position. For example, the patents to Sawby et al., Miller and Seely each disclose a variation of a xe2x80x9clock backxe2x80x9d mechanism. This construction entails forming a notch on a tang of the blade which is engaged by a lug located on the spine of the knife to lock the blade in an open position. A shortcoming of this type of mechanism is that excessive wear can cause the locking mechanism to fail, thereby rendering the knife unsafe for use.
The patents to Neely and Collins each disclose another type of locking mechanism. As disclosed in these patents, a blade has a tang that is engaged by a member to prevent the blade from rotating from its open position. For example, in Collins, a slidable bolt is biased towards the tang to lock the blade in its open position. A shortcoming with Collins""s knife construction is that the bolt is generally parallel with the blade, and the mechanism depends on the spine of the handle for strength. Neely""s knife suffers from the same disadvantage as Collins""s, and from the fact that the blade may be unlocked inadvertently by pulling the blade axially away from the handle during a normal cutting motion of the knife.
What is needed, then, is a stronger lock mechanism than has previously been available for holding a blade of a folding tool in an open, or extended, position, yet which is capable of being manufactured at a reasonable cost.
Such a locking mechanism may beneficially be used in a variety of tools, including tools such as knives and the like that utilize automatic opening mechanisms. When used on a knife, an automatic blade opening mechanism is often generically referred to as a xe2x80x9cswitchblade.xe2x80x9d There are numerous designs for automatic blade opening mechanisms. These include so-called xe2x80x9cfly lockxe2x80x9d devices in which the same mechanism that releases the blade also locks the blade in the open position, and mechanisms that rely upon separate structures to accomplish these functions.
All automatic opening tools include some kind of a spring-like or spring-driven mechanism that urges a blade from the closed position to the open position. In the closed position the blade must be locked against the constant opening force of the spring applied to the blade. Typical springs include spirally wound torsion springs that are wrapped around the pivot axis of the blade and which on one end engage the pivot pin, and on the other engage the blade. Other designs use compression springs and still others use extension springs and spiral wound flat springs and leaf spings. Many automatic opening mechanisms utilize or adapt the well-known sear type of design. Regardless of the particular mechanism used, when the locking mechanism is released, the spring forces the blade into the open position where it may or may not be locked, depending upon the specific design.
The present invention overcomes the above-mentioned shortcomings of the prior art by providing a folding tool comprising an elongate handle defining an elongate groove therein and at least one knife or other tool blade or other tool element pivotally attached to the handle at one end. Each tool blade or element is movable, between a closed position in which it is received within the groove of the handle and an open position in which the blade or tool element is extended away from the handle and exposed. Each tool blade has a working portion that extends away from the handle when in its open position and a tang portion including a locking surface which is located within the groove of the handle when the blade is in its open position. A blade locking pin extends in a direction generally transverse to the length of the handle and blade and has its opposite ends disposed in elongate openings defined in opposite sides of the handle and aligned opposite each other. The blade locking pin is movable with respect to the handle along the elongate openings, between a first position, in which the locking pin engages a locking surface of the tang portion of blade as well as interior surfaces of the elongate openings, to lock the blade in its open position, and a second position in which the pin is spaced away from the locking surface portion of the tang to allow the blade to move from its open position. The blade locking pin is biased toward its first position, but is movable manually to its second position from its first position.
In one embodiment of the invention a locking assembly body is provided to move the locking pin manually from its first position to its second position.
In one embodiment of the invention the blade locking pin is biased toward its first position by a spring housed in a cavity defined within a side wall of the handle.
In one embodiment of the invention a spine portion of the handle is located adjacent the elongate openings in which the ends of the blade locking pin are located, and respective parts of an outer surface of the blade locking pin rest against the locking surface on the tang of the tool blade and a surface of the spine.
In one embodiment the invention provides for such locking of selected one of a plurality of tool blades or elements carried at one end of a handle.
In yet another embodiment the invention provides for an automatic opening mechanism that may be used either with the locking mechanisms described herein or with other locking mechanisms.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.